Television apparatus



R. MLLER ET AL TELEVISION APPARATUS Filed Sept. 7, 1932 Sept. 1l, 1934.

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Patented Sept. 11, 1934 y TELEVISION APPARATUS y Rolf AMller and Georg Schubert, Berlin, Germany, Yassignors to Fernseh Aktien-Gesellschaft, Zehlendorf, near Berlin, Germany Application September 7, 1932, Serial No. 632,038 In Germany September 12, 1931 6 Claims.

This invention relates to television apparatus, and more particularly to an arrangement for the operation of light sources, which make use of a positive column, in conjunction with television receiving apparatus of the type employing a Nipkow disk.

In the case of a relatively large number of image points it is impossible, owing to the poor density of light, to employ the ordinary gaseous 10 conduction lamp hitherto usual in connection with receivers of the kind referred to, and in place thereof it is necessary to make use of brighter sources of light. Gas discharge tubes operating with a positive column have 'been found to be the most suitable for this purpose.

In receiving apparatus of the type employing a' Nipkow `disk it is extremely important to place the source of light, for example the gaseous conduction lamp, as closely aspossible behind the rotating disk. This does not present any diculties in connection with gaseousconduction lamps as hitherto employed, because the cathode surface thereof is equally bright at all points. On the other hand in the case of discharge lamps operating with a positive column an even intensity of the image surface can only be obtained with the assistance of means causing a sufcient dispersion, for instance by the interposition of a piece of milk glass, as the surface in question requires to be illuminated with a luminous tube, which is bent, for example, in meandrian form.

Surface illuminating means operating with a positive column (by this is meant a suitably bent luminous tube having a sheet of milk glass situated in front of the same) cannot, however, readily be employed for television purposes, as strata of light are formed in the luminous column of gas, or in other words the luminous column of gas readily tends to oscillate at a certain frequency.

These disturbances can only be avoided if the temperature of the light source does not sink below a certain value. In accordance, therefore, with the nature of the light source employed, a certain temperature requires to be ensured by way of external heating or, if the temperature is j quire to be heated externally during their operation for the purpose of continuously maintaining a certain quantity of sodium in vaporous form.

It has been found by experiment that particularly in the case of sodium lamps it is extremely vM important to maintain a certain minimum temperature. Sodium light sources, "therefore, have been fitted in a good heat-insulated casing which, for the reasons set forth in thej above, has been covered at the front with a sheet of milk glass. As already stated, this casing, or in other words the milk glass, .requires to be approached as far as possible towards the rotating Nipkow disk. The current of air produced by the rotating disk greatly cools the sheet of glass, and there occur on the one hand the disturbancesabove referred to arising fromr the oscillation, while on the other hand exactly the front portion of the light source becomes clouded, so that great losses of light occur, or operations are rendered entirely impossible. q

Now it is the object of the invention to overcome the difculties referred to, land this is accomplished by the method and meansas described and ascertained in the following with reference to theaccompanying drawing.

Fig. l illustrates in diagrammatical form the method hitherto adopted for approaching the gaseous conduction lamp or surface illuminating :means towards'the Nipkow disk,

Fig. 2 showing insimilar form a possible arrangement according to ithe invention. Y

In Fig. 1 there are shown theNipkow disk 1, the mask or shutter 2, and the surface illuminating means or gaseous conduction lamp 3.

In Fig. 2 there are shown the Nipkow disk 1, the surface illuminating means, i. e., the source of light, and its heating chamber 2, and a wall or partition 3, which is interposed between the light source and the Nipkow disk. This wall may consist of any desired material, and serves to withhold the current of air created by the disk from the heating chamber or casing in which the light source is located. In place of the gate or image aperture there requires to be fitted in the wall 3 a piece of glass or other transparent l95 material 4. In this manner it is accomplished" that a one-sided cooling of the light source or surface illuminating means by reason of the current of air produced by the rotating disk is avoided. Certainly this arrangement is unable to prevent the loss of heat by radiation as regards the heating chamber, and accordingly the source of light, from being greater on the side directed towards the glass than at the remaining points, as

it is not possible to provide heat-insulating accordance with the invention, more greatly irc heated on the front side than at the remaining points, which are well protected against radiation of the heat, by particular location of the heating elements within the chamber or casing. Thus, for example, the arrangement of the heating elements within the chamber or casing may be in the form asillustrated diagrammatically in Fig. 3. l A `I In the latter 1 is the chamber or casing, 2 the heating elements, and 3 the light source tted'in the casing. As shown by the drawing, it is ensured by reason of the arrangement of the heating elements that exactlythe front face 4fis Acon tinuously washed by heated air. v Y

It will be understood that no restriction is .made to the specic form of embodiment illustrated in the drawing, which has been quotedsolely by way of example, and that various modiications are quite possible within the meaning of the above description and the annexed claims without departing from the spirit of the invention.

What We claim as new and desire to secure by Letters Patent is:

,1. Ina television apparatus, a scanning disc, a luminous tube of the positive column type, a casing in which said luminous tube is mounted, said casing being provided with an. aperture for the emission of light rays from said luminous tube, means adapted to keep' the air current produced Tby the rotation of said scanning disc away from .said casing and luminous tube, said .means including a frosted glass plate in front .of said luminous tube, the space between the luminous tube and scanning disc being free of any other equipment, and means for compensating the loss of 'heat caused by said air current.

,2. In a television apparatus, .a scanning disc, a luminous tube of the positive column type, a casing 'having an Vapertured wall in which said luminous tube vis .mounted directly behind said wall, a partition between said scanning disc and the apertured Wall of said casing, a window of heat resisting material in said partition, said partition .being adapted 'to keep air currents produced by. the rotation of said scanning disc away 'A from .said casing, and .means for compensating the 'loss' of 'heat caused by .said air currents.

'front side of said luminous tube.

4. In a television apparatus, a scanning disc, a luminous tube of the positive column type, a

`casing inwhich said luminous tube is mounted,

means between said casing and said scanning disc for keeping air currents produced by the rotation of said scanning disc away from said casing and said luminous tube, and heating elements arranged in said casing in such manner as to compensate the loss of heat caused by said air currents.

5. In a television apparatus, the combination of a scanning disc with a 'luminous tube ofthe positive column type, a Vcasing having an aper-4 tured Wall in'which said luminous tube is mount-j ed directly behind usaid Wall, a partition between said scanningdisc and directly in iront of the apertured wall of said casing, said partition covering the entireone side ofthe scanning disc and being provided `in front of saidapertured wall With a window "plate of heat resisting material, and heating elements within said casi-ng land located adjacent the front of said luminous tube.

6. In a` television apparatus, the combination of a scanning discwith va luminous tube of 'the positive column type, a stationary partition directly adjacent lone side of said `scanning disc and coveringthe entire surface-of the'sa-me, said partition 'beingprovided with an opening, said yluminous tube 'being arranged directly behind fthe opening insaid partition-said partition being adapted tov prevent the coo-lingV of said luminous tube -by the air current yproduced during the `rotation of said scanning disc.v

' 'GEORG CHUBERT.

ROLF MOLLER.

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